Improvised explosive devices (“IEDs”) are insidious tools used by terrorists and insurgents that can cause injury or death to armed service personnel and civilians. Typically constructed with common, inexpensive components, IEDs can be hidden along roads, in vehicles, in buildings, and many other locations, and, thus can hinder the ability of troops to maneuver effectively in combat zones. Most IEDs employ radio receivers and/or low-cost electronic circuits that allow for remote detonation. Critical to reducing the threats posed by IEDs is the development of systems and methods that allow for effective detection and location of IEDs from safe distances.
Electronic devices employing digital and/or analog radio frequency (RF) circuits emit unintended electromagnetic radiation emissions. Although relatively weak, these emissions can be measured to detect, identify, and locate such electronic devices. The ability to detect, identify and localize the source of these unintended emissions is important for IED detection. Electronic devices used in IEDs are typically used as triggers for explosive devices. Such devices are typically off-the-shelf low cost commercial radio receivers, which predominantly includes two types of receiver topologies. A first receiver topology includes those devices employing a superheterodyne receiver, such as cell-phones and walkie-talkies. Super heterodyne receivers typically include a sinusoidal local oscillator (LO) that generates unintended emissions at low levels that can be detected. A second receiver topology includes super regenerative receivers (SRR), which are commonly found in low cost consumer devices, such as wireless doorbells, garage door openers, and the like. These devices do not contain local oscillators and as such, do not normally produce strong unintentional emissions.